1. Field of the Invention
This invention relates to shaft seals and in a preferred embodiment to shaft seals for automotive-type water pumps which are used with coolants containing anticorrosion compounds that can precipitate out.
2. Description of the Prior Art
Automotive type water pumps operate with water and anti-freeze mixtures and often have anti-corrosion compounds (such as anti-rust compounds) added to the mixture. This fact, combined with high speeds and 15 to 50 psi pressures, has required expensive face seals to be used.
While the less expensive elastomeric type shaft seals can be designed to handle the temperatures, speeds and pressures, it has been found that the conditions that occur in water pump seals cause the anti-corrosion compounds to precititate out at the seal/shaft inteface causing rapid wear of the shaft and seal and thus, unacceptably early seal failure.
It is an object of the present invention to overcome these problems in the prior art use of elastomeric type shaft seals for water pumps, such as are used in the automotive field. It is another object of the present invention to provide an inexpensive seal and method for application to water pumps wherein the anti-corrosion materials or compounds are purposely precipitated out at a location separated from the lip of the primary sealing element. It is a further object of this invention to prevent such precipitated-out particles from reaching the lip of the primary sealing element. It is a still further object of this invention to provide a method and seal for sealing fluid containing particles that can cause wear.